Bottom Line:
To embed watermarks into invoice image, the pixels need to be flipped.The more huge the watermark is, the more the pixels need to be flipped.The flippable pixels evaluation mechanism ensures that the pixels keep better connectivity and smoothness and the pattern has highest structural similarity after flipping.

ABSTRACTInvoice printing just has two-color printing, so invoice font image can be seen as binary image. To embed watermarks into invoice image, the pixels need to be flipped. The more huge the watermark is, the more the pixels need to be flipped. We proposed a new pixels flipping method in invoice image for huge watermarking capacity. The pixels flipping method includes one novel interpolation method for binary image, one flippable pixels evaluation mechanism, and one denoising method based on gravity center and chaos degree. The proposed interpolation method ensures that the invoice image keeps features well after scaling. The flippable pixels evaluation mechanism ensures that the pixels keep better connectivity and smoothness and the pattern has highest structural similarity after flipping. The proposed denoising method makes invoice font image smoother and fiter for human vision. Experiments show that the proposed flipping method not only keeps the invoice font structure well but also improves watermarking capacity.

fig7: The summary of score ratio in four most-commonly used font binary images in invoice. In (e), the horizontal axis denotes the different font binary image and the vertical axis is the ratio in total pixels of this font binary image.

Mentions:
The higher score pattern indicates higher priority to flip the center pixel because of keeping good smoothness and connectivity after flipping. Using Wu's method, we flip those flippable pixels whose scores are greater than or equal to 0.3 to ensure the flipped image quality. We summarized the ratio of different score pixels in four most-commonly used invoice font binary images as shown in Figure 7. The invoice is shown in Figure 6.

fig7: The summary of score ratio in four most-commonly used font binary images in invoice. In (e), the horizontal axis denotes the different font binary image and the vertical axis is the ratio in total pixels of this font binary image.

Mentions:
The higher score pattern indicates higher priority to flip the center pixel because of keeping good smoothness and connectivity after flipping. Using Wu's method, we flip those flippable pixels whose scores are greater than or equal to 0.3 to ensure the flipped image quality. We summarized the ratio of different score pixels in four most-commonly used invoice font binary images as shown in Figure 7. The invoice is shown in Figure 6.

Bottom Line:
To embed watermarks into invoice image, the pixels need to be flipped.The more huge the watermark is, the more the pixels need to be flipped.The flippable pixels evaluation mechanism ensures that the pixels keep better connectivity and smoothness and the pattern has highest structural similarity after flipping.

ABSTRACTInvoice printing just has two-color printing, so invoice font image can be seen as binary image. To embed watermarks into invoice image, the pixels need to be flipped. The more huge the watermark is, the more the pixels need to be flipped. We proposed a new pixels flipping method in invoice image for huge watermarking capacity. The pixels flipping method includes one novel interpolation method for binary image, one flippable pixels evaluation mechanism, and one denoising method based on gravity center and chaos degree. The proposed interpolation method ensures that the invoice image keeps features well after scaling. The flippable pixels evaluation mechanism ensures that the pixels keep better connectivity and smoothness and the pattern has highest structural similarity after flipping. The proposed denoising method makes invoice font image smoother and fiter for human vision. Experiments show that the proposed flipping method not only keeps the invoice font structure well but also improves watermarking capacity.